BEIRUT (Reuters) - Iran will never take part in one-sided negotiations with the United States under threat, foreign ministry spokesman Bahram Qassemi said on Wednesday.

His comments appeared to be a reaction to U.S. President Donald Trump's statement on Tuesday that he is ready to "make a real deal" with Iran.

"America should forget forever the idea of one-sided negotiations under the shadow of a threat," Tasnim news agency quoted Qassemi as saying.

According to the IRNA news agency, Qassemi also said that Iran has filed an official letter of objection to the Swiss embassy in Tehran, which oversees U.S. diplomatic relations in the Islamic Republic.

This concerned a speech made by U.S. Secretary of State Mike Pompeo in California on Sunday in which he compared Iran's leaders to a "mafia".